Mortise locksets are a type of lock that is fitted into a rectangular cavity, called a “mortise,” that is cut into the side of a door. Mortise locksets typically comprise a rectangular lock body that is inserted into the mortise, lock trim (including inside and outside trim plates, doorknobs, and/or door handles), a strike plate or box keep that lines a cavity in the door jamb, and a keyed cylinder that operates the locking/unlocking function. A mortise lockset includes a typically self-latching main bolt or latchbolt, and optionally may also include a deadbolt and/or guardbolt. The lock body typically comprises a case assembly and cover that house the keyed cylinder and several levers, springs, and other moving parts used to bias, extend and/or retract the various bolts.
Mortise locksets come in both door-handle locking and door-handle clutching varieties. FIG. 1 illustrates a prior art mortise lockset operable to lock the outside door handle, preventing its further rotation. One disadvantage of door-handle locking locksets is that turning the outside door handle can place a significant amount of potentially damaging torque on the door-handle-locking mechanism inside the lock body. Door-handle clutching locksets, by contrast, selectively mechanically couple the outside door handle with the latch-retracting works inside the lock body. In this type of lockset, a person can turn the outside door handle to a fully-rotated position, but it will not engage the latch. Moreover, applying pressure to the outside door handle does not place the latch-retracting works inside the lock body under potentially damaging loads.
Mortise locksets are also typically (but not always) “handed,” that is, assembled for installation in either a left-hand door or a right-hand door, but not both. Typically, there are at least two handed components of a mortise lock. First, the beveled face of the latchbolt should preferably face the door-closing direction. Second, it is generally preferred that only the outside door handle be access-controlled. The inside door handle should, in most cases, be free at all times to operate the latch-retracting works inside the lock body. Accordingly, the latch-retracting works inside some lock bodies includes two independently spindle-operable hubs, both of which are coupled to a latch-retracting works, but only one of which can be locked or disengaged to prevent access.
To convert a handed mortise lockset assembled for a left-hand installation to one adapted for right-hand installation, or vice-versa, it is often necessary to remove the cover from the case assembly, and then dismount, rotate or reverse, and remount several components (including the latchbolt, guardbolt, and spindle hubs) in the lock body. Often, one or more biasing springs must also be dismounted and remounted—making the conversion process a more difficult and cumbersome process.
FIGS. 1-4b illustrate one example of a conventional left-handed mortise latch and lock body assembly 10. The individual components of the assembly 10 are described in greater detail in the detailed description, below. Converting the left-handed mortise latch and lock body assembly 10 into one adapted for right-hand door installation is a tedious and cumbersome process. First, a locksmith must remove the cover 29 from the case assembly 20. Next, the locksmith must dismount the hub assembly 30 from the case assembly 20 and flip them around, as shown in FIG. 2b. Next, the locksmith must remove the deadbolt link 66 in order to gain access to the guardbolt assembly 70. Next, as shown in FIG. 4b, the locksmith must flip the guardbolt assembly 70 around. Also, as shown in FIG. 3b, the locksmith must flip the latchbolt 51 around. The locksmith must also remount the blocker assembly 80 and deadbolt link 66 and re-attach the cover 29 to the case assembly 20.
Not all mortise locksets require so cumbersome a process to reverse their handing. U.S. Pat. No. 6,619,705 to Dalsing, which is herein incorporated by reference, discloses a clutching mortise lockset that can be converted from a left-handed to a right-handed adaptation, or vice versa, without removing the cover or front plate of the lock body from the case assembly or back plate of the lock body. To convert the internal clutching mechanism from a left-handed to a right-handed outside-door-handle-disabling adaptation, a person can remove a screw 232 from the back plate of the lock body and replace it on the front plate of the lock body (or vice-versa). But with a typical installation, this conversion must be done while the lock body is outside of the door. So if the lock body has already been installed in the mortise of the door, the installer (in most cases) must remove the lock body to gain access to the screw.
There is a need for mortise locks that provide for less cumbersome conversions from a right-handed to a left-handed adaptation, or vice versa. This need is particularly felt for door-handle disabling locksets.
There is also a need for other improvements in mortise locksets. In a typical mortise lockset, the access-controlled operation of the outside door handle is controlled by a finger-operable arrangement (such as a rocker member or two push buttons) mounted through the face plate of the mortise lockset. The finger-operable arrangement typically operates a stop works that locks and unlocks, or a clutch works that engages or disengages, the outside door handle. However, misalignment of the inside and outside door handles can prevent a person from engaging the stop or clutch works.
Accordingly, there is a need for a mortise lock with an improved escapement mechanism that allows a person to activate a stop works or a clutch works even when the inside and outside door handles are misaligned, so that after a person lets go of the handles, and various springs bias the handles back into alignment, the activated stop works or clutch works succeeds in locking or disengaging the outside door handle.
There is also a need for an improved blocker assembly for a mortise lockset. Many high-end mortise locksets include a guardbolt, which is driven into a retracted position when the door is shut, to prevent an intruder from “loiding” the latchbolt open. The retracted guardbolt engages a blocker assembly that blocks the latchbolt assembly from retracting. However, the blocker assembly is disabled if the outside door handle is in a position that is engaged to retract the latchbolt assembly. If the lockset also includes a finger-operable arrangement in the front plate for restoring the outside door handle to an operating condition, there is a danger—particularly with non-deadbolted mortise locks installed in left- or right-handed “reverse” doors (where the door swings out of the access-restricted space)—that an intruder could “card” the finger operable arrangement in order to disable the blocker.
Accordingly, there is also a need for an improved blocker assembly that will prevent an intruder from “loiding” a mortise lock “stop works” or “clutch works” into an outside-door-handle-operating condition.